Solar Simulator

ABSTRACT

An apparatus for testing photovoltaic cells wherein an array of light sources are provided. The light sources can have a collimating lens. In addition, one or more feedback circuits can be provided which monitor and maintain one or more of the light sources.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/475,326, entitled “Solar Simulator”, filed on May 29, 2009, whichitself claims priority to and the benefit of the filing of U.S.Provisional Patent Application Ser. No. 61/057,118, entitled “ShortDistance Solar Simulator”, filed on May 29, 2008, and the specificationsand claims (if any) thereof are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention (Technical Field)

Embodiments of the present invention relate to solar simulators. Moreparticularly, embodiments of the present invention relate to solarsimulators for testing solar cells, particularly in close proximitythereto.

2. Description of Related Art

Typical large area simulators use a single or multiple lamps in a singlelamp house disposed at distance of about a few meters to about 10 metersaway to illuminate large areas. Illumination over the large area isachieved by placing the lamps at this distance away from the solarpanels to be tested. This arrangement takes up a lot of floor space andrequires a large test area. Homogenizing screens may also be used toimprove the uniformity over the area to be tested. High power levelsmust be used in order to drive the lamps sufficiently to achieve thenecessary power at the typical distance of 10 meters. Another issue,which is associated with the known types of large area testers, is theneed for tight divergent angles of the light source on the target. Thisis also achieved by placing the light source at a great distance away.There is thus a need for illumination at low divergent angles, i.e. lessthan 1.5 degrees to as little as 0.2 degrees, for testing largeconcentrator photovoltaic arrays that utilize lenses that require tightdivergent angles which simulate the sun.

BRIEF SUMMARY OF EMBODIMENTS OF THE PRESENT INVENTION

An embodiment of the present invention relates to a photovoltaic testapparatus which includes a light source which light source includes alamp, and at least one honeycomb collimating structure attached thereto.The light source can include a housing disposed between the lamp and thehoneycomb collimating structure. A cell for monitoring an output of thelight source can also be provided, which cell can monitor an intensityand/or color of the light source.

In one embodiment, a feedback circuit for maintaining an output of thelight source within a predetermined range of desired output values canbe provided. A plurality of light sources can be arranged into an array.At least some of the light sources can include a cell for monitoring anoutput of the light source. The test apparatus can include a filter,and/or a homogenizer, which can be a homogenizing lens. The light sourcecan also include one or more connectors.

An embodiment of the present invention also relates to a method fortesting one or more photovoltaic cells which includes forming a lightsource by disposing a honeycomb collimating apparatus to a lamp; placingthe one or more photovoltaic cells in front of the honeycomb collimatingapparatus; causing the light source to emit light; and obtaining areading from at least one of the photovoltaic cells while illuminatedwith light emitted from the light source. Placing the one or morephotovoltaic cells can include placing the one or more photovoltaiccells less than about 5 meters, less than about 3 meters, and/or lessthan about 1 meter from the honeycomb collimating apparatus.

Optionally, the method can include monitoring an output of the lightsource with a cell. The lamp can be adjusted based on a reading from thecell. In the method, forming a light source can also include providingone or more filters, and/or one or more homogenizers. The method canalso include forming an array from a plurality of light sources, whichcan be done by joining a plurality of light sources with one or moreconnectors. The method can also include monitoring at least one of theplurality of light sources with a cell, and can optionally includeadjusting a lamp of at least one source based on a reading obtained fromthe cell.

Objects, advantages and novel features, and further scope ofapplicability of the present invention will be set forth in part in thedetailed description to follow, taken in conjunction with theaccompanying drawings, and in part will become apparent to those skilledin the art upon examination of the following, or may be learned bypractice of the invention. The objects and advantages of the inventionmay be realized and attained by means of the instrumentalities andcombinations particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The accompanying drawings, which are incorporated into and form a partof the specification, illustrate one or more embodiments of the presentinvention and, together with the description, serve to explain theprinciples of the invention. The drawings are only for the purpose ofillustrating one or more preferred embodiments of the invention and arenot to be construed as limiting the invention. In the drawings:

FIG. 1 is a perspective view drawing illustrating a single lamp houseaccording to an embodiment of the present invention; and

FIG. 2 is a perspective view drawing which illustrates an array of lamphouses of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As used throughout the specification and claims, the term “lamp” isintended to include any device, apparatus, or system capable ofgenerating light, including but not limited to all electrically-poweredlights. The term “lamp” can thus include, but is not limited to, one ormore light emitting diodes, incandescent lamps, florescent lamps, arclamps, as well as combinations thereof.

As used throughout the specification and claims, the term “honeycomb” isintended to include any structure capable of collimating light due tothe light having traveled through a plurality of elongated at leastsubstantially parallel openings.

Embodiments of the present invention can be used for irradiating a largearea solar panel. As illustrated in FIG. 1, light source 10 preferablycomprises a pulsed or continuous source lamp 12, connected to acollimator 14. Although collimator 14 can be formed from one or morelenses, in a preferred embodiment, a honeycomb type of structure ispreferably used to reduce cost. Collimator 12 can optionally be coupledto lamp 10 via housing 16. In a further embodiment, one or more filters18 can optionally be placed between lamp 10 and collimator 14. Filters18 can optionally comprise one or more diffusers, one or morecollimating elements, homogenizing lenses, or other homogenizers. Theoutput of light source 10 is preferably highly collimated.

In one embodiment, each light source 10, or groups thereof, canoptionally have reference cell 20 for measuring the output of thatsource 10 or group of sources. Cell 20 can be a photovoltaic cell or aphoto sensor. The output of cell 20 is preferably used in conjunctionwith a processor, microcontroller, other circuit, or combinationsthereof, to provide feedback and control of source 10 or that group ofsources, thereby improving the shot to shot light uniformity andautomated matching between sources 10 of one or more arrays 22 (see FIG.2). In one embodiment, one or more connectors 21 are preferably providedon one or more sides of light source 10 which permit a plurality oflight sources 10 to be physically connected to one another, therebycreating array 22. Connectors 21 can be any type of connector capable ofjoining, at least temporarily, a plurality of light sources 10,including but not limited to latch connectors, hook connectors, pinconnectors combinations thereof, and the like.

In a preferred embodiment, each light source 10 preferably has its ownlamp 12 and is controlled separately from at least some of the lightsources 10 of array 22. In one embodiment, cell 20 is preferably used tomonitor light intensity and/or frequency/wavelength, thus permitting thepower applied to lamp 12 to be regulated such that intensity and/oruniformity for source 10 is maintained at a desired level. Singlesources 10 or groups thereof can optionally be driven together to reducethe cost of individual drivers for each source in some applications.

FIG. 2 illustrates an embodiment of the present invention wherein array22 of individual light sources 10 is provided. The output of the arrayedsystem can illuminate horizontally and/or vertically and can be lessthan 5 meters, less than 3 meters, and in some embodiments, less thanone meter away from the solar cells or photovoltaic module or panelunder test. In one embodiment, each light source is preferablyindividually computer controlled, and the illuminated area can beadjusted to match the size of the panel by simply adding or removing (orturning on or off) individual light sources 10 of array 22.

In one embodiment, the present invention does not comprise a collimatinglens.

Large Area Arrays

Embodiments of the present invention preferably allow the user to testboth terrestrial and space solar arrays in a much smaller area due tothe close proximity which can be achieved between the light source andthe solar panels under test.

Highly Collimated Single Light Source

Embodiments of the present invention can be used for single moduletesting (i.e. less than about 11 inches square as well as large areatesting form about 12 inches square to grater than about 4 meterssquare. This is optionally achieved by mounting modules in series and/orparallel arrays.

Although the invention has been described in detail with particularreference to these preferred embodiments, other embodiments can achievethe same results. Variations and modifications of the present inventionwill be obvious to those skilled in the art and it is intended to coverin the appended claims all such modifications and equivalents. Theentire disclosures of all references, applications, patents, andpublications cited above are hereby incorporated by reference.

What is claimed is:
 1. A photovoltaic test apparatus comprising: a lightsource comprising: a lamp; a collimating lens; and a cell, said cellmonitoring an intensity of said lamp; and a feedback circuit formaintaining the intensity of said lamp; and a plurality of said lightsources arranged into an array.
 2. The apparatus of claim 1 wherein saidlight source further comprises a housing disposed between said lamp andsaid collimating lens.
 3. The apparatus of claim 1 wherein said cellmonitors a color of said lamp.
 4. The apparatus of claim 3 wherein saidfeedback circuit maintains the color of said lamp.
 5. The apparatus ofclaim 1 further comprising a color monitoring cell positioned to monitora color of said lamp.
 6. The apparatus of claim 5 wherein said feedbackcircuit also maintains the color of said lamp.
 7. The apparatus of claim1 wherein each of said light source further comprises one or morearray-positioning connectors which connect said light source togetherwith another of said light source to form said array.
 8. A photovoltaictest apparatus comprising: a light source comprising: a lamp; acollimating lens; and a cell, said cell monitoring a color of said lamp;and a feedback circuit for maintaining the color of said lamp; and aplurality of said light sources arranged into an array.
 9. The apparatusof claim 8 wherein said light source further comprises a housingdisposed between said lamp and said collimating lens.
 10. The apparatusof claim 8 wherein each of said light source further comprises one ormore array-positioning connectors which connect said light sourcetogether with another of said light source to form said array.
 11. Aphotovoltaic test apparatus comprising: a light source comprising: alamp; and a collimating lens; a plurality of said light sources arrangedinto an array; at least one cell, said cell monitoring an intensity of agroup of one or more of said light sources; and a feedback circuit formaintaining the intensity of said group of one or more of said lightsources.
 12. The apparatus of claim 11 wherein said light source furthercomprises a housing disposed between said lamp and said collimatinglens.
 13. The apparatus of claim 11 wherein said cell monitors a colorof said lamp.
 14. The apparatus of claim 13 wherein said feedbackcircuit maintains the color of said lamp.
 15. The apparatus of claim 11wherein each of said light source further comprises one or morearray-positioning connectors which connect said light source togetherwith another of said light source to form said array.
 16. A photovoltaictest apparatus comprising: a light source comprising: a lamp; and acollimating lens; a plurality of said light sources arranged into anarray; at least one cell, said cell monitoring a color of a group of oneor more of said light sources; and a feedback circuit for maintainingthe color of said group of one or more of said light sources.
 17. Theapparatus of claim 16 wherein said light source further comprises ahousing disposed between said lamp and said collimating lens.
 18. Theapparatus of claim 16 further comprising a light intensity monitoringcell positioned to monitor a light intensity of at least one of saidlight sources
 19. The apparatus of claim 18 wherein said feedbackcircuit also maintains the light intensity of at least one of saidlamps.
 20. The apparatus of claim 16 wherein each of said light sourcefurther comprises one or more array-positioning connectors which connectsaid light source together with another of said light source to formsaid array.